Nanomagnet based memory and logic operations are of great technological interest due to their non-volatility, ultrahigh density, unlimited endurance and thermal robustness. Nanomagnets are the key elements of any spintronic devices and they are a potential alternative to current semiconductor technology which has reached its limits in terms of integration density and low power operation.
In this context, recent attempts are noted for the rapid commercialization of magnetic random access memory (MRAM) which is known as universal memory. Nanomagnet based devices rely on manipulating the magnetic ground state. Nanomagnetic logic has been realized using magnetic quantum-dot cellular automata (MQCA) approach and the operation of majority logic gate has been demonstrated in such systems. In such systems binary information is stored into bistable units and the information is processed through dipolar-coupled chains leading to ferromagnetic (FM) and/or antiferromagnetic (AFM) ordering for appropriately structured arrays.
Dipolar coupling driven AFM ground state requires a carefully adjusted field initialization process and it is susceptible to imperfection due to fabrication limitations. To date most of the studies on such coupled chains are explored by studying their magnetic ground states using magnetic force microscopy (MFM) and tuned for different logic operations, however, functionality of such architecture based on their collective dynamic behaviour has not been explored or achieved. These prior attempts have resulted in various problems, such as for example, susceptible operation due to fabrication defects, low reliability in large area arrays of nanomagnets with non-uniform magnetic states and switching, susceptible operation due to magnetostatic interactions in closely spaced devices, bias field to hold a particular magnetic state, and/or complexity in clocking field application for reliable operation in dipolar coupling driven devices.
The example embodiments described herein seek to address or at least alleviate the above problems.